AB0643 Are there any distinctive finding in ANCA-associated vasculitis related pulmonary involvement in comparison with Connective Tissue Diseae or Idiopatic pulmonary fibrosis
Authors: E. Durak Ediboglu, Ş. Karasu, T. Ekici, M. O. Turan, Ö. Gerçik, D. Solmaz, C. Gümüş, S. Akar
Journal: Annals of the Rheumatic Diseases (2022)

Background Patients with ANCA associated vasculitis (AAV) have a wide spectrum of pulmonary involvement from parenchymal necrotizing granuloma formation, trecheobronchial inflammation, pulmonary capillaritis to interstitial lung disease. Pulmonary involvement is relatively common in connective tissue diseases (CTDs). Both rheumatologic disorders and idiopatic pulmonary fibrosis (IPF) might cause the usual interstitial pneumonia (UIP) pattern. However, little is known regarding the clinical and radiologic similarities/ dissimilarities of those diseases. Objectives We aimed to evaluate the thoracic computed tomography (CT) findings of patients with AAV, CTDs-related interstitial lung disease (ILD) or IPF. Methods Patients whose thoracic CT performed at the time of the diagnosis or relapse of AAV (n=64), at the time of the diagnosis of CTD related ILD (n=55) or IPF (n=52) were included in the analysis. Demographic, clinical and serological data were collected retrospectively. Radiological patterns of pulmonary involvement were evaluated by two expert pumonary radiologists and abnormal thoracic CT findings were classified according to Fleischner Society guidelines. Intra- and inter-observer variation were calculated. Multoniminal logistic reggresion was performed to identfy disease specific findings in thoracic CT. Results A total of 171 patients were included and of them 64 patients (62.5% with granulomatosis with polyangiitis, 37.5% with microscopic polyangiitis) in AAV group, 55 patients in CTD related ILD (50.9% with scleroderma, 40.0% with rheumatoid arthritis, 9.1% other or undifferensiye connective tisue disease) group and 52 patients in IPF group. Demographic and thoracic CT findings were summarized in Table 1. In univariate analysis according to Fleishner Society definition, patients with AAV had more common pulmonary noduls, cavities, consolidation. However, patients with AAV were less likely to have interlobular septal thickening (ILST), lymph node adenopathy (LAP) and reticulation compared to both CTD related ILD and IPF. In addition, among those groups of rheumatic diseases, cavities and alveolar hemorrhage were detected only AAV. In multinominal logistic reggresion, the presence of nodul and consolidation and the absence of ILST and mediastinal LAP were independent determinant findings in thoracic CT in patients with AAV in comparison with both CTD related ILD or IPF. Table 1. Demoraphic characteristics and Thoracic CT findings of patients AAV patients (n=64) CTD related ILD (n=55) IPF (n=52) p Characteristics Age at diagnosis, yrs, mean (SD) 58.6 (15.0) 61.8 (12.0) 72.4 (9.4) &lt;0.001 Sex, male, % 70.3 30.9 75 &lt;0.001 Smoking, ever, % 77.8 26.5 62.8 0.29 Chest CT findings according to Fleishner guideline, % Ground glass opasity 29.7 38.2 9.6 0.003 Reticulation 19.0 52.7 94.2 &lt;0.001 Interlobular septal thickening 28.6 69.1 98.1 &lt;0.001 Peribronchial thickening 11.1 20.0 3.8 0.03 Honeycombing 14.3 25.5 63.5 &lt;0.001 Bronchiectasis 31.3 47.3 86.5 &lt;0.001 Consolidation 45.3 12.7 5.8 &lt;0.001 Micronodules 6.3 3.6 0 0.07 Nodules 45.3 10.9 3.8 &lt;0.001 Cavities 23.4 0 0 &lt;0.001 Eymphysema 18.8 7.3 19.2 0.96 Mosaic attenuation pattern 7.8 20 38.5 &lt;0.001 Alveolar hemorrage 17.2 0 0 &lt;0.001 Mediastinal lymph node adenopathy 26.7 53.7 57.7 0.002 Pleural effusion 14.1 1.8 0 0.001 Pericardial effusion 6.3 9.1 0 0.16 Conclusion The results of this study show that in additon to clinical and labaratory characteristics, some thoracic CT imaging findings like the presence of nodules and consolidation and the abscence of LAP and ILST may be useful to differentiate pulmonary involvement of AAV from other relatively common rheumatologic conditions and IPF. In addition, alveolar hemorrhage and cavities may be particular manifestations of AAV. Disclosure of Interests None declared